The present invention generally relates to a device for preventing axial movement of any elongated member applied through the skin of a mammal at a puncturing position. Accordingly, the purpose of such a device is to keep said elongated member applied through the skin of a mammal for different reasons. Such an elongated member is mostly stiff and sharp, so that it may be pearced through the skin of said mammal, normally a human being, but it may also be flexible, such as a catheter, which has been pearced through the skin by using a cannula needle thereafter retracted.
More specifically, the invention relates to such a device comprising a plaster designed to cover the surface around the puncturing position and having at least an adhesive layer for securing it to the skin as well as an opening through the layer(-s) thereof for the passage of said elongated member therethrough. The plaster is used for securing the needle on the skin. By this the patient also has a visible security against the needle falling out.
A device of this type may for instance be used for preventing axial movement of a cannula needle when carrying out hemo-dialysis, in which the blood of a patient suffering from impaired kidney function is conducted from a patient blood vessel to a dialysis machine and is returned to the patient after treatment. In such a case two cannula needles may be used, one for draining blood from the patient and the other for returning the treated blood thereto. It is in this case of vital importance that a said device is extremely reliable, since it would of course be a catastrophe if the cannula needle returning the blood to the patient would move out of the correct position, so that blood would only be drained from the body of the patient without being returned. However, in this case also a single needle may be used. When a single needle is used, the blood is received from the patient and transferred back to the patient through the same needle. The needle is, in its turn, connected to a tube that is split up into two parts, one for venous blood and one for arterial blood.
Devices of this type are disclosed in for example DE 3105187, DE 19508073 and U.S. Pat. No. 5,087,248. These devices use the material of the plaster for keeping the cannula needle, catheter or the like in position. However, this material may be stretched or partially torn apart would the patient move, so that there is a risk that the elongated member moves axially. These devices also use an adhesive to keep the elongated member in place by securing wings attached to the elongated member to the skin, so that it is important that this adhesive binds strongly enough to said wings. In the case of a cannula needle, this is very thin, so it is necessary to apply an adhesive tape or the like on wings provided extra therefor at a remarkable distance from the needle portions penetrating the skin.
A device according to the preamble of appended claim 1 is known through WO 97/21459. The clamping means used for keeping the needle in place is rather complicated to the construction and is not able to hold the needle as firm as desired in some situations.
Furthermore, it may be mentioned that U.S. Pat. No. 6,231,548 and U.S. Pat. No. 5,084,026 disclose devices of another type differing from the present invention by the fact that the plaster thereof is not penetrated by the elongated member, so that the plaster does not cover the surface around the puncturing position of the elongated member. A plaster is there instead used to be carried for other means holding the elongated member in place. The devices are rather complex, secure the elongated member at a considerable distance from the puncturing position and do not use the plaster to cover the surface around the puncturing position.